The present invention relates to a technique to detect hybridization. More particularly, the present invention relates to a technique to detect hybridization which is so designed as to move by dielectrophoresis a target nucleic acid to a site where a nucleic acid for detection is fixed.
It has recently become common practice to use an integrated substrate for bioassay which has DNA molecules of prescribed species minutely arranged thereon by microarray technology. The integrated substrate, which is called DNA chip or DNA microarray (the former terminology is used in the present invention), is used to analyze gene mutation, SNPs (simple nucleotide polymorphism), and gene expression frequency. It will find use in broad areas including drug development, clinical diagnosis, pharmacogenomics, evolution research, and legal medicine.
The DNA chip is a glass substrate or silicon substrate on which are integrated a variety of and a large number of DNA oligochains or cDNA (complementary DNA). Consequently, the DNA chip of the invention permits comprehensive analysis of hybridization. The background and related art of the present invention will be described in the following.
JP-A-2001-507441 discloses a tiny electrophoresis chip which is designed to move or separate charged molecules such as nucleic acid, through a channel formed in a substrate, the channel having tiny electrodes arranged therein which produce an electric field to move or separate the charged molecules in the channel. This related art technology suggests that electrophoresis is commonly used to move or separate charged molecules such as nucleic acid.
Japanese Patent Laid-open No. 2003-75302 (particularly claim 1 and Paragraph 0027) discloses an apparatus to move a charged substance with polarity. This apparatus consists of a substrate and a plurality of electrodes arranged in a prescribed direction. A voltage with a reverse polarity of the charged substance is applied to a section of the electrodes. This procedure is repeated sequentially for adjacent sections, so that the charged substance is moved in the direction in which the electrodes are arranged. Further, the configuration in which a surface of an electrode to be used is covered with an insulating film is also disclosed.
Japanese Patent Laid-open No. 2004-135512 discloses an apparatus which has scanning electrodes arranged in the reaction region, such that when a voltage is applied across adjacent electrodes, nucleic acid molecules are attracted and fixed to the electrode edges as if they span from one electrode to another.